1. Field of the Invention
The present invention pertains to a clutch disk comprising a hub area and a friction lining assembly supported in a radially outer part of the hub area.
2. Description of the Related Art
In clutch disks of this type, the friction lining assembly is designed to be clamped between opposing friction surfaces of a flywheel and, for example, a pressure plate so that torque can be transmitted. In slip mode, however, that is, when there is relative motion between the friction lining assembly and the flywheel or pressure plate, there is the danger that so-called frictional vibrations can be excited, which can lead to acoustically perceivable low-frequency vibrations, especially when several areas are being excited in phase with each other, and also to variations in the frictional force or torque being transmitted, which is referred to as xe2x80x9cgrabbingxe2x80x9d. So that rotational irregularities occurring in the drive state can be absorbed or damped, clutch disks are often designed with so-called torsional vibration dampers, in which damping springs act in the path of torque transmission between a friction lining assembly and the power take-off area, which can be, for example, an area of the clutch disk connected to the transmission input shaft. The stiffness of these damper springs, however, is optimized for the rotational vibrations to be expected in the rotational mode. The frictional vibrations comprising different frequencies and amplitudes, however, cannot usually be damped by damper springs of this type.
It is the task of the present invention to provide a clutch disk in which the occurrence of frictional vibrations can be avoided almost completely.
This task is accomplished in accordance with the invention by a clutch disk comprising a hub area and a friction lining assembly carried on a radially outer part of the hub area.
In addition, a damper mass assembly is also provided, which can move in the circumferential direction around a rotational axis with respect to the friction lining assembly and with respect to the hub area against the action of an elastic support device.
The damper mass assembly provided in the clutch disk according to the invention can vibrate freely relative to the friction lining assembly and/or relative to the hub area under the elastic effect of the support device and thus, upon excitation of frictional vibrations, can build up an opposing vibration, which ultimately contributes to the cancelling-out of the frictional vibrations. By appropriate selection of the elasticity of the support device and of the mass of the damper mass assembly or of the shape of this assembly, the system can be tuned to specific excitation frequencies. In this way, primarily the system-specific and the generally known natural frequencies of the frictional vibrations can be damped.
To cancel out or to damp the frictional vibrations as efficiently as possible, it is proposed that the area where the mass of the damper mass assembly which makes the most essential contribution to the damping of the vibrations be located radially in the area of the friction lining assembly.
It can be provided, for example, that the friction lining assembly has a plurality of friction lining elements arranged in sequence around the circumference around the axis of rotation, and that a part of the damper mass is provided between at least two of the friction lining elements arranged in sequence around the circumference. In this case, it is advantageous for the damper mass part to be supported in the circumferential direction relative to at least one of the two friction lining elements or one of the support areas of the hub area carrying these elements by the elastic support device.
To ensure here at the same time that excessive radial load on the elastic support device cannot occur, it is also possible to provide a circumferential movement guide device for the minimum of one damper mass part, by means of which this part is guided as it moves in the circumferential direction and supported radially from the outside against the centrifugal forces which develop.
For example, the design can be such that the hub area comprises two cover disk elements, which are a certain axial distance apart and the radially outer areas of which carry the friction lining elements, at least one of these cover disk elements extending radially outward over the minimum of one damper mass part to provide the circumferential movement guide device. In this case, it is advantageous for the hub area to have a central disk element, which is supported relative to the disk cover elements by way of a damper element assembly and which is designed to be connected to a shaft.
In an alternative embodiment, it can be provided that the damper mass assembly is supported relative to a part of the hub area carrying the friction lining assembly by a plurality of damper elements, which essentially constitute the elastic support device. Here the design can be such that the damper mass assembly comprises two cover disk elements, one of which is located on each axial side of a central disk element, which carries the friction lining assembly, the radially outer area of the cover disks carrying a plurality of damper mass parts. The damper elements are supported against the cover disk elements and the central disk element. The central disk element is preferably designed to be connected to a shaft.
To ensure in the clutch disk according to the invention that, regardless of the instantaneous torque being transmitted via the clutch disk, the damper mass assembly can optimally fulfill the function for which it is originally intended, namely, the function of cancelling out or damping frictional vibrations, it is proposed that the damper mass assembly not be installed in the path of torque transmission of the clutch disk.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.